Hartmetalleinsatz und Gesteinsbohrer

ABSTRACT

The invention relates to a carbide insert ( 2 ) for a rock drill ( 1 ), which is configured as a non-percussively operating twist drill with a cylindrical drill body ( 11 ) and a working end ( 13 ) having the carbide insert ( 2 ), the carbide insert ( 2 ) having two cutting lips ( 22 ) which are radially opposite one another relative to an axis of drill rotation (d) and are arranged at an angle to one another to form a centering tip ( 21 ) and with each of which a peripheral conveyor spiral ( 14 ) may be associated. To be able to introduce a drilled hole more quickly, easily and simply and with less risk of damage into a workpiece of rock, rock-like material, hard plastics, glass or the like, it is proposed that the cutting lips ( 22 ) be configured asymmetrically to one another, wherein at least one of the cutting lips ( 22 ) defines over its radial profile, in a central region spaced from its radial ends, a tip ( 23 ) projecting in the drilling direction (b).

The invention relates to a carbide insert for a rock drill, which is configured as a non-percussively operating twist drill for drilling rock, rock-like material, hard plastics, glass or the like with a cylindrical drill body and a working end having the carbide insert, the carbide insert having two cutting lips which are radially opposite one another relative to an axis of drill rotation and are arranged at an angle to one another to form a centering tip and with each of which a peripheral conveyor spiral is associated. The invention further relates to a rock drill with the carbide insert.

When drilling rocks, rock-like material, hard plastics, glass or the like non-percussively, the problem arises that it is very difficult and time-consuming to introduce a drilled hole due to the lack of impact. On the other hand, percussive drilling cannot be used since such materials then have a tendency to break and chip off easily, which may even go as far as to destroy the workpiece in question. For example, in the case of a glazed wall tile of rock-like composite material, first of all the hard and brittle glaze on the front thereof and then the comparatively softer body of the wall tile have to be drilled through, which requires significant experience on the part of the drill operator.

One object of the invention is to provide a carbide insert of the above type or a rock drill with this carbide insert by means of which a drilled hole can be introduced more quickly, easily and simply and with less risk of damage into a workpiece of rock, rock-like material, hard plastics, glass or the like.

The object addressed is achieved according to the invention by the features of claim 1. Advantageous further developments are described in the subclaims. The object addressed is achieved by the cutting lips simply being configured asymmetrically to one another, wherein at least one of the cutting lips defines over its radial profile, in a central region spaced from its radial ends, a tip projecting in the drilling direction for initiating transverse motion.

The asymmetry is thus manifested in that the at least one cutting lip comprises the tip projecting in the drilling direction. As a result of this asymmetry, the cutting behavior of the two cutting lips differs. During drilling, a transverse force is exerted on the rock drill by the tip projecting in the drilling direction by means of which force the rock drill is pushed away in a predominantly radial direction and thus forced into transverse motion. The rock drill may be pushed away in the direction away from the tip and towards the respective other cutting lip. In this way, the other cutting lip is accordingly pushed harder against the bottom of the drilled hole, which in turn assists or initiates radial counterpressure and thus countermotion to the pushing away of the rock drill. In the case of percussive drilling, percussive motion is exerted in the drilling direction on the bottom of the drilled hole, whereby the latter is subjected to very severe alternating loads. The transverse motion initiated by the tip acts transversely of the drilling direction, however, and thus incomparably more gently on the workpiece than percussive drilling, such that drilled holes can be introduced quickly and gently even into sensitive, brittle materials such as tiles and glass.

In particular, the rock drill enters into a transverse motion which oscillates relative to the drilling direction. The transverse motion may also be described as wobble. As a result of simultaneous rotation of the rock drill, the transverse motion of the working end sweeps the entire cross-sectional area of the bottom of the drilled hole and thereby leads, depending on the material to be drilled, to easier and more effective comminution by scraping, attrition, crushing, crumbling or the like of the material at the bottom of the drilled hole. As a consequence of this transverse motion, the material at the bottom of the drilled hole is loosened without drilling pressure having to be built up at the bottom of said hole, which leads to the risk of the material bounding the drilled hole being destroyed. According to the applicant's tests, the material is comminuted to a greater degree by the carbide insert according to the invention or by the rock drill having this carbide insert than in the case of comparable rock drills of the type in question, such that this material may more readily be discharged contrary to the drilling direction. In addition, the tip generally constitutes a discontinuity of the cutting lip over the radial profile thereof, wherein at this location continuous cutting is interrupted and thus a break is produced relative to the radially adjacent material. The material at the bottom of the drilled hole is thus comminuted to a greater degree on removal and may therefore be more readily transported away from the drill tip contrary to the drilling direction.

The at least one cutting lip may comprise precisely one tip protruding in the drilling direction. It may in particular have just this one tip. In particular, the tip may extend with its lateral flanks over the entire radial extent of the at least one cutting lip. The tip may have one free end with an end point. The end point is arranged at a specific radius relative to the axis of drill rotation.

The cutting lips may be arranged radially opposite one another. They may converge in the middle in the manner of a roof to form the centering tip.

This tip may be rounded at the end. It may take the form of a projection. With regard to reduced friction losses and thus heating at the bottom of the drilled hole, it is proposed that the tip itself protrude radially to the right and left of same out of a continuous shape profile of the at least one cutting lip. The tip may itself constitute at the end a discontinuity in the shape profile of the at least one cutting lip.

In particular, the entire cutting lip forms this one tip. The tip may extend over the entire or virtually the entire cutting lip and terminate at a specific radius with its free end in an end point. Preferably, the entire cutting lip is divided into two portions, which are arranged angled relative to one another in the manner of a gable, so forming the tip. In particular, the cutting lip converges from its two radial ends to the tip. It may structurally advantageously simply be provided that the tip of the at least one cutting lip is defined radially inwardly and radially outwardly in each case by an uncurved or by a concavely curved free-running surface. Although a tip defined by uncurved free-running faces may be regarded as more robust with regard to wear and/or to damage than a tip defined by curved free-running faces, it may also at the same time be regarded as less sharp or less effective with regard to generating the oscillating reciprocating motion. Therefore, the carbide insert and thus the rock drill with the carbide insert may be adapted to specific materials to be drilled by way of the configuration of the tip.

The cutting edge of the cutting lip may be formed by the associated free-running faces and the associated body faces sloping contrary to the drilling direction of the carbide insert. Preferably, the entire cutting edge of the at least one cutting lip is defined by these free-running faces with the body faces of the carbide insert sloping contrary to the drilling direction. In one advantageous configuration of the carbide insert, the tip of the at least one cutting lip is defined radially inwardly and radially outwardly by an uncurved or by a concavely curved free-running surface.

The profile of the cutting edge of the at least one cutting lip may comprise, relative to a radial-axial plane comprising the drilling direction, two straight lines converging at the tip in the case of uncurved free-running surfaces or two concave arcs converging at the tip in the case of curved free-running surfaces. In the case of a plate-like configuration of the carbide insert with a height direction extending in the drilling direction and, arranged in each case perpendicular to one another, with a thickness direction and width direction, said radial-axial plane is arranged perpendicular to the thickness direction.

The tip of the at least one cutting lip may alternatively be formed radially inwardly by an uncurved free-running surface and radially outwardly by a concavely curved free-running surface or, conversely, radially inwardly by a curved free-running surface and radially outwardly by a concavely uncurved free-running surface. The curved free-running surface may define part of a semi- or partly cylindrical volume.

As is generally conventional, the free-running surfaces of the cutting lips adjoin one another radially in the middle, so forming a transverse lip. The axis of rotation preferably intersects the transverse lip.

The relative radial position of the tip over the at least one cutting lip may have a decisive influence on the oscillating transverse motion. The further away the tip is arranged from the axis of drill rotation, the greater is the radial lever of the transverse force caused by the tip and thus the effect of the wobble resulting from oscillating transverse motion.

In particular, the tip may divide the cutting lip into two radial portions, i.e. a radially outer portion and a radially inner portion. The ratio of the length of the outer portion to that of the inner portion may be 1, preferably 2 or 4. The greater the ratio, the further radially outwards is the tip and the greater is the transverse force to be expected.

Another further development of the carbide insert may provide for the centering tip to be tapered preferably axially symmetrically relative to the axis of rotation. A first flute-like recess in a leading position relative to the associated cutting lip in the direction of drill rotation and extending to the or into the associated conveyor spiral, in particular at an angle of less than 60°, preferably less than 30° to the radial direction of the associated cutting lip, may be provided radially inwardly per cutting lip. Said recess may be introduced into the cutting lip. With this bilateral tapering into the centering tip, the cutting lip may be extended into the centering tip effectively with regard to cutting.

Furthermore, a second flute-like recess extending into the associated conveyor spiral may be introduced into the drill body solely or additionally radially outwardly, in each case in a leading position relative to the cutting lip in the direction of drill rotation and in particular at an angle of less than 60° to the radial direction of the associated cutting lip.

The cutting edge may thus in each case form a boundary for the first and/or the second recess and is formed with and by introduction of the respective recess.

The recesses may in each case extend from the associated cutting lip to the conveyor spiral associated with this cutting lip and possibly lead thereinto. They thus enable improved discharge of the material removed by drilling contrary to the drilling direction in the form of powder, grit and/or particles. The recesses may each be of concave configuration. They may each define part of a partly to semi-cylindrical volume.

Furthermore, the two recesses of a cutting lip may each form a region of this cutting lip and adjoin one another radially, so forming a discontinuity in the radial profile of the cutting lip. This discontinuity may, as described above in connection with the tip, bring about breaking of the cut material, whereby this may be comminuted and thus more readily transported away.

Advantageously in this regard, the discontinuity formed by the mutually adjoining recesses may be arranged at a radial point of the cutting lip which is different from the free end point of the tip of this cutting lip. Provision may in particular be made for the discontinuity, formed by the mutually adjoining recesses, of the cutting lip to be arranged radially inwards relative to the tip of this cutting lip. This discontinuity, formed by the mutually adjoining recesses, of the cutting lip may be a tip pointing in the circumferential direction which does not project in the drilling direction.

The first flute-like recess may be arranged to extend radially beyond the center axis of the carbide insert. This may form a radially inner region of the associated cutting lip and a radially inner region of the free-running edge associated with the other cutting lip.

In particular, the first recess and/or second recess may be arranged angled by an angle of attack towards the axis of drill rotation in the drilling direction. The recesses may be arranged inclined relative to one another towards the axis of drill rotation in the drilling direction.

With provision of the first recess, the geometry of the centering tip may thus also be decisively modified to the effect that, depending on the depth of the first recess, the above-described transverse lip, which in itself can only be considered to have a scraping cutting, can be reduced in favor of extension of the cutting lip. It is however considered advantageous, for the sake of the robustness and stability of the centering tip, to keep the transverse lip and thus the thickness of the centering tip small. Advantageously, the length of the transverse lip may amount to a few or up to three or up to six decimillimeters. It may amount to up to 5% or 3% of the diameter of the masonry drill.

The centering angle of the centering tip may also influence the transverse motion, since the greater the centering angle, the smaller a centering action of the centering tip may be and the greater may be the possible transverse motion of the rock drill, counteracting centering, during drilling. Provision may in particular be made for the centering tip to have a centering angle which amounts for drilling of for example glass to preferably 50° to 70°, for drilling of for example wall tiles to 70° to 80° or for drilling of for example floor tiles, thermosets and hard composites to 110° to 140°.

In one further development of the carbide insert, the two cutting lips may each have the tip projecting in the drilling direction. To achieve an asymmetric action and thus generate the transverse motion, it is advantageous for the tip of the one cutting lip to be arranged at a first radius which is different from a second radius of the tip of the other cutting lip. Provision may in particular be made for the first radius to be larger than the second radius by up to 90%, preferably by up to 60% and in particular by up to 30%. The applicant's tests in this respect demonstrate the tendency of material removal to become more intense as the difference between these two radii increases. It is advantageous for the tip of the one cutting lip to be arranged on the radially inner half of the cutting lip and that of the other cutting lip to be arranged on the radially outer half of the other cutting lip.

The carbide insert may advantageously be simply of plate-shaped configuration. It may be sintered as a blank in its basic shape, with the desired geometries thereof then being provided by post-machining.

In particular, on the side with the cutting lip, the carbide insert may be adapted such that, in the installation position, it merges without transition, i.e. without projections, shoulders or the like which inhibit the conveying stream of particles to be carried away, into the associated conveyor spiral in the intended conveying direction. To this end, in addition to the above-described recesses, an additional cut-away portion may be provided in a trailing position relative thereto in the drilling direction, which cut-away portion hollows out the underside of the carbide insert to such an extent that the cut-away portion merges without transition into the conveyor spiral.

The present invention is explained in greater detail below with reference to a number of embodiments depicted in drawings of the carbide insert or of the rock drill with carbide insert, without however limiting the invention to said embodiments. In the drawings:

FIGS. 1 and 1 a respectively show side views of a rock drill with a carbide insert according to FIG. 3 and an enlarged detail Ia according to FIG. 1,

FIGS. 2 and 2 a respectively show another side view of the rock drill according to FIG. 1 and an enlarged detail IIa according to FIG. 2,

FIGS. 3a to 3h each show a view of the carbide insert shown in FIGS. 1 and 2,

FIGS. 4a to 4d each show a view of a further embodiment of the carbide insert,

FIGS. 5a to 5c each show a view of a further embodiment of the carbide insert,

FIGS. 6a and 6b respectively show a view of a further embodiment of the carbide insert and an enlarged detail thereof,

FIGS. 6c and 6d respectively show a view of a further embodiment of the carbide insert and an enlarged detail thereof,

FIGS. 7a to 7e each show a view of a further embodiment of the carbide insert and

FIGS. 8a to 8e each show a view of a further embodiment of the carbide insert.

FIGS. 1 and 2 each show a side view of a rock drill 1, which is configured as a non-percussively operating twist drill for drilling rock, rock-like material, hard plastics, glass or the like with a cylindrical drill body 11 and a working end 13 having a receptacle 12, a plate-shaped carbide insert 2 according to the embodiments shown in FIGS. 4a-4e being brazed into the receptacle 12. FIGS. 3 and 5-8 show further embodiments of the carbide insert 2 in various views and in part with associated enlarged details.

As is apparent from the enlarged details of FIGS. 1a and 2a associated respectively with FIG. 1 and FIG. 2 and from the other FIGS. 3-8, the carbide insert 2 has cutting lips 22 which are radially opposite one another relative to an axis of drill rotation d and are arranged at an angle to one another to form a centering tip 21. Each cutting lip 22 has a conveyor spiral 14 associated with it, by which the cut material, not shown here, cut away by the carbide insert 22 is transported away contrary to drilling direction b. (In the figures, in the case of larger, curved side faces, additional lines with a smaller line thickness are drawn in which do not indicate a contour but rather a depth profile of these side faces.)

The cutting lips 22 are asymmetric to one another in all the embodiments of the carbide insert 22, wherein at least one of the cutting lips 22 defines over its radial profile, in a central region spaced from its radial ends, a tip 23 projecting in the drilling direction b thereof. The tip 23 represents a discontinuity in the radial profile of the cutting lips 22. In all the embodiments, a single projecting tip 23, where provided, is arranged in the cutting lip 22. The tip 23 projecting in the drilling direction b, as described above, generates a transverse force during drilling, which forces the rock drill into transverse motion perpendicular to the drilling direction b and rotating with the drill, whereby the material at the bottom of the drilled hole is removed more quickly and moreover in the form of finer to floury grains, without percussive drilling being used.

The tip 23 extends over the entire cutting lip 22 and ends at a specific radius with its free end in an end point. The tip 23 thus rises over the entire cutting lip 22 from both radial sides to the free end point.

In the embodiments of the carbide insert 2, the tip 23 is defined radially inwardly and radially outwardly by free-running surfaces 24 of the cutting lip 22. The free-running surfaces 24 may here, as shown by way of example in FIGS. 1-4 and 7, be uncurved side faces which slope away from the cutting edge 25 of the cutting lip 22 in each case at a specific wedge angle to the axis of drill rotation d contrary to drilling direction b. With regard to a radial axial plane, which in FIG. 3f is the same as the image plane, the cutting lip 22 has a gable-like profile. In FIG. 3f , to clarify the roof-like profile of the cutting lips 22 with the tip 23, the profile of the cutting lip 22 without tip 23 on the right here is shown reflected by dash-dotted lines and denoted 22′. These two profiles form a triangle with a height h. It is immediately clear from the drawing that the smaller the internal angle α formed by the tip 23 and the greater the height h of the triangle drawn, the greater is the transverse force caused by the tip 23 during drilling. The cutting edge 25 of the cutting lip 22 with tip 23 is formed by the associated free-running surface 24 and the side face 26 sloping away contrary to the drilling direction b and pointing in the direction of drill rotation r. The tip 23 thus takes the shape of a three-sided pyramid with the two free-running surfaces 24 and the side face 26 as side faces of said pyramid. The proportions shown in the figures are however merely by way of example and it is not intended to limit the disclosure content of the invention thereto.

Alternatively, the free-running surfaces 24 defining the tip 23 may be concavely curved, as shown by way of example in FIGS. 5 and 8. As in FIG. 3f , in FIG. 5a the profile of the cutting lip is shown in a side view perpendicular to the radial axial plane, which at the same time is the image plane of FIG. 5a . According thereto, the profile is gable-like but with curved “gable sides”, i.e. with two concave arcs converging at the tip. The exact profile is introduced using cylindrical grinding wheels, wherein the wedge angle is defined at the same time thereby. Thus, compared to the embodiments of the carbide insert 2 with uncurved free-running surfaces 24, a sharper tip 23 is produced, which is more aggressive in action but more susceptible to wear.

As is clearly apparent in particular from FIGS. 3f and 5a , the tip 23 divides the cutting lips 22 into two radial portions, i.e. a radially outer portion a1 and a radially inner portion a2, wherein the ratio of the length of the outer portion a1 to that of the inner portion a2 here amounts to around 1.5.

In contrast to the embodiments of the hard metal insert 2 according to FIGS. 1-6, those in FIGS. 7 and 8 have just one tip 33 in leading position in the direction of drill rotation r on each of the two cutting lips 32, wherein the tips 33 are however arranged at different radii, i.e., as shown in FIG. 7a , the left-hand tip 33 is arranged at a first radius r1 and the right-hand tip 33 at a second radius r2, wherein the first radius r1 is here about half as large as the second radius r2. The tip 33 on the right hand here, due to its greater radial lever (r2), thus causes a greater transverse force to be generated than the left-hand tip 33.

The centering tip 21 is axially symmetrically tapered relative to the axis of drill rotation d. To this end, a first flute-like recess 271 in a leading position relative to the cutting edge 25 of the cutting lips 22 in the direction of drill rotation r and extending to the associated conveyor spiral 14 of the respective cutting lip 22, is provided radially inwardly for each cutting lip 22. The first recess 271 is introduced into the carbide insert 2, forming an inner region and thus parallel to this inner region. The cutting lip 22 is thus extended into the centering tip 21 and it is moreover ensured that cut-off material may be discharged from the centering tip 21 into the respective conveyor spiral.

Furthermore, the first recess 271 is arranged inclined at an angle of attack γ to the axis of drill rotation d. As is apparent for example from FIG. 6c or 6 d, the two cutting lips 22 extend radially inwards, forming a transverse lip 28, wherein they are radially spaced by way of the transverse lip 28, depending on the size of the angle of attack γ. A comparison of FIGS. 3a, 6a and 6c shows that, the greater the angle of attack γ or the further the first recesses 271 extend relative to the axis of drill rotation d, the smaller is the transverse lip 28. The inclination of the first recess 271 may thus be used purposefully to adjust the size of the transverse lip 28 and thus also the radial thickness of the centering tip 21. The first flute-like recess 271 forms the radially inner region 221 of the one cutting lip 22 and a radially inner region 241 of a free-running edge 242 defining the free-running surface 24 of the other cutting lips 22.

In the embodiments of the rock drill 1 or of the carbide insert 2 illustrated here, the centering angle β amounts to around 120° and is thus suitable in particular for drilling floor tiles, thermosets, hard composites and the like.

In the embodiments of the carbide insert 2 according to FIGS. 6-8, in addition to the first recess 271, a second recess 272 is provided radially outwardly and extending to the cutting edge 25 for further improved removal of cut material, said second recess extending towards the respectively associated conveyor spiral 14 contrary to the drilling direction b. The two recesses 271, 272 of a cutting lip 22 adjoin one another, forming a discontinuity in the radial profile of the associated cutting lips 22 which likewise contributes to comminution of the cut material. In a manner favorable to maximum comminution, it is here provided that, in all the embodiments of the carbide insert 2 shown here, the radial point P at which the two recesses 271, 272 adjoin one another radially is different from the point at which the tip 23 ends at its free end.

In order to ensure maximally free flow of the cut-off material from the carbide insert 2 into the respective conveyor spiral 14 of the rock drill 1, a cut-away portion 29 is provided (in particular in FIGS. 1, 1 a, 2 and 2 a and in the views from below according to FIGS. 3e and 4e ) axially in the drilling direction b in a trailing position relative to the cutting lip 22, wherein that cut-away portion merges into the associated conveyor spiral virtually without transition contrary to the drilling direction b, i.e. without any side face pointing in the drilling direction b and projecting away into the convey spiral 14 for transporting the material away. That is to say, in the embodiments of the carbide insert 2 shown here, all that has been provided is an offset which is harmless to material flow at the point of transition of the carbide insert 2 into the conveyor spiral 14.

Insofar as a second recess 272 is provided, same conveys the cut material contrary to drilling direction b into the associated cut-away portion 29. In addition, the first recess 271 guides the cut material into the associated second recess 272 and radially inwards directly into the associated cut-away portion 29. Comprehensive removal of the cut material into the associated conveyor spiral 14 is thus made possible.

The carbide insert 2 is dimensioned radially and arranged in the receptacle 12 in such a way that it terminates radially outwardly flush with the drill body 11.

LIST OF REFERENCE NUMERALS

-   1 Rock drill -   11 Drill body -   12 Receptacle -   13 Working end -   14 Conveyor spiral -   2 Carbide insert -   21 Centering tip -   22 Cutting lip -   221 Inner region (cutting lip) -   23 Tip -   24 Free-running surface -   241 Inner region, free-running surface -   25 Cutting edge -   26 Side face (cutting edge) -   271 First recess -   272 Second recess -   28 Transverse lip -   29 Cut-away portion -   α Internal angle -   β Centering angle -   γ Angle of attack -   a1 Outer portion -   a2 Inner portion -   b Drilling direction -   d Axis of drill rotation -   h Height -   r Direction of drill rotation -   r1 First radius -   r2 Second radius -   P Point 

1. A carbide insert (2) for a rock drill (1), which is configured as a non-percussively operating twist drill for drilling rock, rock-like material, hard plastics, glass or the like with a cylindrical drill body (11) and a working end (13) having the carbide insert (2), the carbide insert (2) comprising: two cutting lips (22) which are radially opposite one another relative to an axis of drill rotation (d) and are arranged at an angle to one another to form a centering tip (21) and with each of which a peripheral conveyor spiral (14) is associated, the cutting lips (22) being configured asymmetrically to one another, at least one of the cutting lips (22) defining over its radial profile, in a central region spaced from its radial ends, a tip (23) projecting in the drilling direction (b), the centering tip (21) being axially symmetrically tapered relative to the axis of drill rotation (d) and the carbide insert being of plate-shaped configuration, a first flute-like recess (271) in a leading position relative to a cutting edge (25) of one of the cutting lips (22) in the direction of drill rotation (r) and extending into the associated conveyor spiral (14) is introduced (A5) radially inwardly and/or a second flute-like recess (272) in a leading position relative to a cutting edge (25) of the other cutting lip (22) in the direction of drill rotation (r) and extending into the associated conveyor spiral (14) is introduced (A5) radially outwardly into the drill body (11), and in that the two recesses (271, 272) each form a profile portion of the associated cutting lip (22) and adjoin one another radially, so forming a discontinuity in the radial profile of the cutting lip (22).
 2. The carbide insert (2) as claimed in claim 1, wherein the tip (23) of at least one cutting lip (22) is defined radially inwardly and radially outwardly by an uncurved or by a concavely curved free-running surface (24).
 3. The carbide insert (2) as claimed in claim 1, wherein the tip (23) divides the cutting lip (22) into a radially outer portion (a1) and a radially inner portion (a2), the ratio of the length of the outer portion (a1) to that of the inner portion (a2) is ≤1.
 4. (canceled)
 5. (canceled)
 6. (canceled)
 7. The carbide insert (2) as claimed in claim 1, wherein the discontinuity formed by the mutually adjoining recesses (271, 272) is arranged at a radial point (P) of one cutting lip (22) which is different from the free end point of the tip (23) of this cutting lip (22).
 8. The carbide insert (2) as claimed in claim 7, wherein the point (P) with the discontinuity of one cutting lip (22) formed by the mutually adjoining recesses (271, 272) is arranged radially inwardly relative to the tip (23) of this cutting lip (22).
 9. The carbide insert (2) as claimed claim 8, wherein the first recess (271) and/or second recess (272) are arranged in the drilling direction (b) angled towards the axis of drill rotation (d) at an angle to same.
 10. The carbide insert (2) as claimed in claim 9, wherein the two cutting lips (22) each have the tip (23) projecting in the drilling direction (b), wherein the tip (23) of the one cutting lip (22) is arranged at a first radius (r1) which is different from a second radius (r2) of the tip (23) of the other cutting lip (22).
 11. The carbide insert (2) as claimed in claim 10, wherein the tip (23) of one cutting lip (22) is arranged on the radially inner half of the cutting lip (22) and the tip (23) of the other cutting lip (22) is arranged on the radially outer half of the other cutting lip (22).
 12. The carbide insert (2) as claimed in claim 11, wherein the centering tip (21) has a centering angle (β) which amounts for drilling of glass to 50° to 70°, wall tiles to 70° to 80° or floor tiles, thermosets and hard composites to 110° to 140°.
 13. (canceled)
 14. A rock drill (1) configured as a non-percussively operating twist drill for drilling rock, rock-like material, hard plastics, glass or the like, wherein the rock drill (1) has a cylindrical drill body (11) and a working end (13) with a carbide insert (2) as claimed in claim
 1. 15. The rock drill (1) as claimed in claim 14, wherein the carbide insert (2), includes a first flute-like recess (271) in a leading position relative to the cutting edge (25) of the cutting lip (22) in the direction of drill rotation (r) and extending into the associated conveyor spiral (14) is introduced radially inwardly and/or a second flute-like recess (272) in a leading position relative to the cutting edge (25) of the cutting lip (22) in the direction of drill rotation (r) and extending into the associated conveyor spiral (14) is introduced radially outwardly into the drill body (11), wherein the recesses (271, 272) of the cutting lip (22) extend contrary to the drilling direction (b) to the conveyor spiral (14) associated with this cutting lip (22) or lead into the conveyor spiral (14) associated with this cutting lip (22).
 16. The rock drill (1) as claimed in claim 15, wherein the first recess (271) of the cutting lip (22) leads, contrary to the drilling direction (b), into the second recess (272) associated with this cutting lip (22) and the second recess in turn leads, contrary to the drilling direction (b), into the conveyor spiral (14) associated with this cutting lip (22).
 17. The carbide insert (2) as claimed claim 1, wherein the first recess (271) and/or second recess (272) are arranged in the drilling direction (b) angled towards the axis of drill rotation (d) at an angle to same.
 18. The carbide insert (2) as claimed in claim 17, wherein the two cutting lips (22) each have the tip (23) projecting in the drilling direction (b), the tip (23) of one cutting lip (22) is arranged at a first radius (r1) which is different from a second radius (r2) of the tip (23) of the other cutting lip (22).
 19. The carbide insert (2) as claimed in claim 18, wherein the tip (23) of one cutting lip (22) is arranged on the radially inner half of the cutting lip (22) and the tip (23) of the other cutting lip (22) is arranged on the radially outer half of the other cutting lip (22).
 20. The carbide insert (2) as claimed in claim 19, wherein the centering tip (21) has a centering angle (β) which amounts for drilling of glass to 50° to 70°, wall tiles to 70° to 80° or floor tiles, thermosets and hard composites to 110° to 140°.
 21. The carbide insert (2) as claimed in claim 17, wherein the two cutting lips (22) each have the tip (23) projecting in the drilling direction (b), the tip (23) of the one cutting lip (22) is arranged at a first radius (r1) which is different from a second radius (r2) of the tip (23) of the other cutting lip (22).
 22. The carbide insert (2) as claimed in claim 1, wherein the two cutting lips (22) each have the tip (23) projecting in the drilling direction (b), the tip (23) of the one cutting lip (22) is arranged at a first radius (r1) which is different from a second radius (r2) of the tip (23) of the other cutting lip (22).
 23. The carbide insert (2) as claimed in claim 1, wherein the tip (23) divides the cutting lip (22) into a radially outer portion (a1) and a radially inner portion (a2), wherein the ratio of the length of the outer portion (a1) to that of the inner portion (a2) is ≤½.
 24. The carbide insert (2) as claimed in claim 1, wherein the tip (23) divides the cutting lip (22) into a radially outer portion (a1) and a radially inner portion (a2), the ratio of the length of the outer portion (a1) to that of the inner portion (a2) is ≤⅓. 